Rotary internal combustion engine

ABSTRACT

There is provided a rotary internal combustion engine ( 20 ) comprising a plurality of rotors ( 21 ) each having a plurality of lobes ( 22 ) for intermeshing with lobes of other rotors to form successive combustion chambers. Axial seal elements ( 60, 61 ) are provided at the rotor tips and trailing tips of the rotors respectively. Circumferential axial edge seals ( 59 ) are also provided to interconnect the axial seals. The seals engage sealing plates ( 30 ) on each axial side of an engine housing ( 29 ) so as to effect the combustion chambers. Fuel inlets and ignition means are provided at suitable locations, as are exhaust means.

This invention relates to a rotary internal combustion engine. Rotaryengines have a number of advantages over standard reciprocating engines.One advantage is the much smaller number of moving parts needed. Inaddition, with reciprocating engines a considerable amount of energy iswasted in stopping parts and then causing them to move in the oppositedirection. Much vibration, heat and wear results from this.

According to a first aspect of the present invention there is provided arotary internal combustion engine comprising two rotors mounted within ahousing for rotation about respective central axes which aresubstantially parallel to each other, each rotor having a series ofradially projecting lobes which are equally spaced circumferentially andwhich intermesh with the lobes of the other rotor to form successivecombustion chambers as the rotors rotate, said housing being providedwith a sealing plate on each axial side of the rotors, the sealingplates being in sealing engagement over an active area which axiallyseals each combustion chamber formed by the rotating intermeshing rotorsthroughout a full combustion cycle.

Preferably four intermeshing rotors are provided in two pairs, thecentral axes of the rotors being provided on the corners of a square,each pair of rotors providing said successive combustion chambers whichare axially sealed by said sealing plates. In a preferred embodimenteach sealing plate is generally diamond shaped, the short axis of whichis generally parallel to imaginary lines extending between the centralaxes of each pair of rotors.

Another preferred feature is that the axially inward facing surface ofone of the sealing plates is provided with a groove arrangement tofacilitate escape of exhaust gasses. Ideally the groove arrangementcomprises a central exhaust through bore equidistant from the centralaxes of all four rotors, with four angled grooves extending from thecentral bore towards the edges of the sealing plate. In somearrangements both sealing plates are provided with one of said groovearrangements.

A further preferred feature is that the peripheral edge of each sealingplate tapers outwardly in a direction axially away from the rotors. Alsoat least one of the sealing plates provides orifices for fuel deliveryto the combustion chamber and at least one of the sealing platesprovides ignition means.

According to a second aspect of the present invention there is provideda drive arrangement incorporating a rotary internal combustion enginecomprising two rotors mounted within a housing for rotation aboutrespective central axes which are substantially parallel to each other,each rotor having a series of radially projecting lobes which areequally spaced circumferentially and which intermesh with the lobes ofthe other rotor to form successive, sealed combustion chambers as therotors rotate, the rotors each having a shaft which extends through thehousing to engage a drive system for driving a driven member in rotationrelative to the housing about a drive axis.

In a preferred arrangement the drive arrangement is mounted on an axlehaving the central drive axis, the housing is fixed relative to the axleand the drive member is driven in rotation about the axle and also thedriven member is a wheel with a bearing disposed between the wheel andthe axle.

Preferably the rotors are mounted in bearings in the housing and alsothe rotor shafts extending through the housing are attached to drivecogs which mesh with a cooperating drive ring mounted on the wheel.

It is a preferred feature that the axle incorporates an axial throughbore for exhaust products, fuel delivery and electricity delivery forignition means where necessary and a central tube for exhaust productsis provided in the axial through bore and extends through the housing.In addition the housing is provided with communication means for thefuel delivery, electricity delivery for ignition means where necessaryand for exhaust products.

Conveniently four intermeshing rotors are provided in two pairs, thecentral axes of the rotors being provided on the corners of a square,each pair of rotors providing said successive, sealed combustionchambers.

According to a third aspect of the present invention there is provided arotary internal combustion engine comprising two rotors mounted within ahousing for rotation about respective central axes which aresubstantially parallel to each other, each rotor having a series ofradially projecting lobes which are equally spaced circumferentially andwhich intermesh with the lobes of the other rotor to form successivesealed combustion chambers, each lobe having a tip and a leading face inthe direction of rotation, each tip and each leading face being providedwith an axially extending strip seal arrangement each comprising anaxially extending through slot formed in the rotor and a pair of axialseal elements retained in the slot, the axial seal segments each havinga portion projecting beyond the rotor and being of the same axial lengthas the rotor.

With a preferred arrangement each axial face of each rotor is formedwith a peripheral groove which communicates with the through slots andwhich houses an edge seal which sealingly links the axial seal segments.In some arrangements the edge seal for one axial face of each rotor isformed in lengths, each length being integrally formed with one of theaxial seal segments of at least one pair of axial seal segments.Conveniently the edge seal for one axial face of each rotor is formedintegrally with one of the axial seal segments of all of the pairs ofaxial seal segments, the edge seal for the other axial face being formedintegrally with the other axial seal segments of all the pairs of axialseal segments.

Preferably the axial seal segments at the tips are urged radiallyoutwardly and the axial seal segments in the leading faces are urgedoutwardly in the direction of rotor rotation. In one embodiment theaxial seal segments at each rotor tip are urged radially outwardly byweights received in respective bores which communicate with the axialslot so that the weights can contact the inner ends of the axial sealsegments and each rotor tip has two of said bores which are angled andwhich extend from opposite respective axial faces of the rotor, crossinside the lobe and extend to the axial slot. With some arrangementseach pair of axial seal segments in each leading face is urged by springmeans.

In certain preferred embodiments the edge seals are urged axiallyoutwards by spring means. Conveniently said spring means comprises anumber of through bores extending between the grooves on opposite axialfaces, each through bore accommodating a spring disposed between twopistons to urge them into engagement with the oppositely disposed edgeseals.

It is a preferred feature that each axial through slot has a firstsection opening to a second section inwardly thereof, the second sectionbeing wider than the first section such that the axial slot retains theaxial seal segments and also that each pair of axial seal segments aremirror images of each other and have abutting planar surfaces.

Embodiments of the present invention will now be described in moredetail. The description makes reference to the accompanying drawings inwhich:

FIGS. 1a to 1 e are schematic plan views of a rotary engine according tothe present invention,

FIG. 2 is a section on line II—II of FIG. 1b,

FIG. 3 is a central lengthwise section through a wheel unitincorporating a rotary engine similar to that shown in FIGS. 1 and 2,

FIG. 4 is a central lengthwise section through an alternative wheel unitincorporating a rotary engine similar to that shown in FIGS. 1 and 2,

FIG. 5 is a schematic side view of the wheel unit of FIG. 4,

FIG. 6 is a detailed central lengthwise section through a further wheelunit incorporating a rotary engine as shown in FIGS. 1 and 2,

FIG. 7 is a perspective view of a part of one rotor of the engine shownin FIG. 1,

FIG. 8 is a perspective view of a seal arrangement for use in the rotorshown in FIG. 7,

FIG. 9 is an axial view of part of the rotor/seal combination,

FIG. 10 is a perspective view of part of an alternative sealarrangement,

FIG. 11 is a simplified section on a radial plane through a lobe of arotor, and

FIG. 12 is an exploded perspective view of part of a rotor and sealarrangement.

In the figures there are shown a number of embodiments of a rotaryinternal combustion engine 20 which is of the general type shown in GB2313627A. In such engines 20 rotors 21 are provided with tooth-likeprojecting lobes 22 which intermesh with each other as shown in FIGS. 1ato 1 e. In FIGS. 1a to 1 e four rotors 21 a to 21 d are provided in asquare arrangement. The respective rotors rotate in the direction ofarrows 23 about respective axes 24 a to 24 d.

The shape of the lobes 22 of the rotors 21 is such that a succession ofcombustion chambers are formed as the rotors 21 rotate. In the areabetween each pair of lobes 22 there is a communication port, shown inthis embodiment as a groove 25, which enables gases to move from achamber at the leading face of a lobe to a chamber at the trailing faceof the lobe and this will become clearer in due course.

FIG. 1a also shows fuel injection points 26 and ignition means 27although if the engine 20 is a diesel engine then the ignition means 27will not be required. The injection points 26 and ignition means havenot been shown in FIGS. 1b to 1 e to prevent congestion of the drawings.

As shown in FIGS. 1 and 2, the rotors 21 a to 21 d are mounted onrespective shafts 28 a to 28 d and are disposed within an engine housing29. On each axial face of the housing 29 is a sealing plate 30 which inthis embodiment is generally diamond shaped. Clearly the combustionchambers of the engine 20 must be sealed in order for the engine tooperate and so the rotors are provided with suitable seals around theperimeters of their axial faces and at the radially outermost tips 31 ofthe lobes 22 and at the rearmost points 32 of the lobes 22.

The dimensions of the sealing plates 30 are such that they do not extendover the entire axial area defined by the rotors 21. Instead the areascovered by the sealing plates 30 are the areas defined by the sealedcombustion chambers as they perform the operating cycle of the engine.Some extra area is covered as a safety margin and so that each sealingplate 30 is an easily formable shape.

It will also be seen from FIG. 2 that the sealing plates 30 taper attheir outermost edges 33 to provide lead-in surfaces for the seals asthey approach the areas in which sealed combustion chambers are to beformed.

The reduced dimensions of the sealing plates 30 compared to the entireaxial area defined by the rotors reduce the friction between the rotors21 and the stationery parts of the engine 20. The result of this isimproved engine efficiency and reduced wear on the sealing arrangement.

The sealing plate 30 on at least one axial side of the rotors 20 is alsoprovided with a series of grooves 34 which terminate at a centralopening 35 in the sealing plate 30 and engine housing 29. The grooves 34and opening 35 facilitate the escape of the exhaust gases from thecombustion chambers.

FIGS. 1a to 1 e show the basic cycle of operation of the engine 20. Thecycle of operation of the engine will, however, only be discussedbriefly as it is already known from GB 2313627A. Concentrating on asingle chamber X, in FIG. 1a it is still in an open, induction stage. InFIG. 1b chamber X is sealed and the induced fuel/air mixture starts tobe compressed. Compression continues in FIG. 1c and in FIG. 1d the gasesmove from the leading face to the trailing face of the lobe 22 by virtueof the groove 25 in the valley between the adjacent lobes. In FIG. 1ethere is ignition. After ignition there is expansion, with chamber X nowbeing indicated by chamber X′ in FIG. 1a and 1 b. In FIG. 1c, chamber X′opens to exhaust and this continues in FIGS. 1d and 1 e.

In FIGS. 3 to 6 there are shown applications of the engine 20. FIG. 3shows a wheel arrangement 40 comprising a rotary engine 20 of thegeneral type discussed above coupled to a wheel 41 having a wheel rim42. Attached to the wheel rim 42 would be some form of tyre, but thishas not been shown. The wheel 41 also incorporates a brake disc 43 butthe remainder of the brake arrangement has not been shown and thismethod of braking is shown only as an example.

The engine housing 29 incorporates a fixed axle 44 and a cover plate 45.The shafts of the rotors 21 are mounted in bearings 46 in the housingand two of the four shafts are attached to drive cogs 47. The drive cogs47 mesh with a drive ring 48 which is fixedly mounted on the wheel 41.This is more clearly shown in FIG. 5. The wheel 41 in turn is mountedfor rotation about the axle 44 by virtue of a bearing 49. The axle 44 ishollow and communicates with a central exhaust opening 35 of the enginehousing 29. The hollow axle 44 also provides a route for the otherengine services, i.e. fuel inlets to supply the fuel injection points 26and electricity supply for the ignition means 27 which are not shown inFIG. 3.

It will be understood that operation of the engine 20 will causerotation of the rotors 21 within the housing 29. This will effectrotation of the drive cogs 47 which will via the drive ring 48, rotatethe wheel 41 relative to the axle 44.

The arrangement shown in FIG. 4 is very similar to the embodiment shownin FIG. 3 and so like parts have been given the same reference numerals.The principal difference between the two constructions is that in FIG. 4the fixed axle 44 is not hollow. Fuel and electricity are suppliedexternally into the cover plate 45 and exhaust products escape directlythrough a central opening 35 in the cover plate 45. The invention is notlimited to the illustrated arrangements however.

FIG. 6 shows a detail of an arrangement similar to that shown in FIG. 3and so like parts have again been given like reference numerals. In thisarrangement the housing 45 has a sealing plate 30 on each axial side ofthe arrangement of rotors 20 as discussed above in connection with FIGS.1 and 2. FIG. 6 also shows more detail of a central exhaust passage 50communicating with the central exhaust opening 35 of the inner sealingplate 30. The figure shows inlet tubes 51 and wires 52 for supplyingfuel and electricity respectively to the fuel injection points andignition means.

Suitable arrangements for effectively sealing the combustion chambersare shown more clearly with reference to FIGS. 7 to 12. In FIG. 7 thereis shown part of one rotor 21, a pair of lobes 22 and a transfer groove25 being clearly visible. Each axial face 53 of the rotor 21 is providedwith a shallow groove 54 which extends around the periphery of the rotor21. At the radially outermost tip 31 of each lobe 22 is an axiallyextending slot 55 which extends from one axial face 53 to the other. Thetrailing tip 32 of each lobe 22 is also provided with an axiallyextending slot 56 which extends from one axial face 53 to the other. Theslots 55, 56 interrupt the shallow groove 54 on each axial face of therotor 21. Each slot 55, 56 has an axially extending opening 57 which isnarrower than the interior portion 58 of the slot, the junction betweenthe narrow and wider portions being tapered.

The shallow grooves 54 accommodate elongate edge seals 59 which in FIG.8 are shown as being continuous around the entire periphery of eachaxial face of the rotor 21. Depending from the edge seal 59 at suitablelocations are axial seal elements 60 which have one side shaped forengagement with corresponding axial seal elements 61 depending from theelongate edge seal 59 for the other axial face of the rotor 21.

Each pair of corresponding axial seal elements 60, 61 are disposed inone of the slots 55, 56 and are shown in this arrangement has havingflat inner surfaces 62 in abutment with each other. The outer surfaces63 are shaped to fit the opening 57, tapered portion and the interiorportion of the slots 55, 56. The free ends 64 of the axial seal elements60, 61 project in use externally of the rotor 21 so as to form sealingpoints.

It will be seen that notches 65 are formed in the free ends of the axialseal elements remote from the edge seal 59 for accommodating the edgeseal 59 of the seal for the other axial side of the rotor 21. The freeends 64 of the axial seal elements 60, 61 are, however, not interruptedby the notches 65 and remain continuous for the full axial width of theaxial seal elements 60, 61.

In FIG. 10 there is shown an alternative seal arrangement which issimilar to FIG. 8 in many respects and so like parts have been given thesame reference numerals. Essentially in FIG. 10 the elongate edge seals59 are split into sections which combine to form a complete sealarrangement.

In FIGS. 11 and 12 are shown non-limiting examples of possiblearrangements for urging the seals 59, 60 and 61 outwards into sealingengagement with the surfaces with which seals are to be formed. FIG. 11shows two angled bores 66 each of which extends between the axial faceof the rotor 21 and the slot 55 at the lobe tip 31. A pair of such bores66 are provided for each lobe 22. In each bore 66 is a weight 67 and thepair of weights 67 for each lobe 22 act to urge the axial seal elements60, 61 outwardly by virtue of centrifugal force when the rotors 21 arerotating.

In FIG. 12 there is shown a method for urging the edge seals 59 axiallyoutwards. A number of axially extending through holes are formed in therotor so as to interconnect the shallow grooves 54 on both axial sidesof the rotor 21. In each hole is provided a spring 68 and a pair of rods69, one on each axial side of the spring 68. The spring 68 and rods 69are inserted prior to the elongate seals 59 being inserted into theshallow groove 54 and act to urge the elongate seals axially outwards.Equal force is thus exerted on the seals 59 on each axial side of therotor 21.

It will be appreciated that other methods could be used to bias the sealelements 60, 61 outwardly such as springs and also to bias the elongateseals 59 axially outwards.

Although the above embodiments have all been described with reference toan engine 20 having four rotors 21 arranged in a square formation andhaving eight lobes 22, it will be understood by the skilled person thatother arrangements are possible with different numbers of rotors andlobes. Also, other lobe shapes are possible as long as sealed combustionchambers can be formed.

With four rotors having for example eight protrusions each, it ispossible to achieve 210 degrees of combustion in one cycle, i.e. onecomplete revolution of the rotors. However, the invention is not limitedto the use of four rotors. For example, by axially overlaying one set ofrotors with a second set, on the same shafts and angularly offsettingthe second set by, 11.5 degrees with respect to the first set, it ispossible to achieve continuous combustion.

Moreover four or more rotors can be intermeshed in the same plane, toincrease the overall capacity, producing a large flat engine. Typicallyfour rotors each with eight protrusions can reasonably provide an engineof about 240 cc capacity, but this is just a non-limiting example.However, the capacity can be varied by using axially thicker or thinnerrotors or by increasing the size of the rotors in both directions.

However, in the case of a motor vehicle, it is envisaged that an enginein accordance with the invention, which can be flat, could be providedfor, and fit neatly in each wheel of that vehicle, for example inassociation with electronic control, and/or gearbox, and/or torqueconverter, and/or clutch, or conceivably even by direct drive associatedwith means for immobilising the vehicle until the engines are rotatingsufficiently fast to fire.

By virtue of electronic or computer control, it will then be possible toadjust the speed of each wheel according to the required road speed ofthe wheel, i.e. when cornering, and to prevent wheel slip onaccelerating and deceleration or braking, this would allow vehicles withmultiple wheels to become all wheel drive, and conceivably all wheelsteering.

In addition, in relation to FIGS. 3 to 6 the engine 20 is shown as partof a wheel arrangement. Other drive arrangements are, however, possibleinstead of a drive for a wheel. For example, the wheel could be replacedby a propeller for an aircraft or for a watercraft or for a landcraftsuch as a hovercraft.

List of Reference Numerals 20 Engine 21 Rotor 22 Lobe 23 Rotationdirection 24 Axis of rotation 25 Communication port, groove. 26 Fuelinjection point 27 Ignition means 28 Shaft 29 Housing 30 Sealing plate31 Lobe tip 32 Lobe rearmost point 33 Sealing plate edge 34 Groove 35Central opening 40 Wheel arrangement 41 Wheel 42 Wheel rim 43 Brake disc44 Fixed axle 45 Cover plate 46 Bearing 47 Drive cogs 48 Drive ring 49Bearing 50 Exhaust passage 51 Inlet tubes 52 Wires 53 Axial face ofrotor 54 Shallow groove 55 Axial slot 56 Axial slot 57 Axial opening 58Interior portion 59 Edge seal 60 Axial seal element 61 Axial sealelement 62 Inner surface of axial seal element 63 Outer surface of axialseal element 64 Free end of axial seal element 65 Notch 66 Angled bore67 Weight 68 Spring 69 Rod

What is claimed is:
 1. A rotary internal combustion engine comprisingtwo rotors mounted within a housing for rotation about respectivecentral axes which are substantially parallel to each other, each rotorhaving a series of radially projecting lobes which are equally spacedcircumferentially and which intermesh with the lobes of the other rotorto form successive combustion chambers as the rotors rotate, saidhousing being provided with a sealing plate on each axial side of therotors, the sealing plates being in sealing engagement over an activearea which axially seals each combustion chamber formed by the rotatingintermeshing rotors throughout a full combustion cycle, wherein theperipheral edge of each sealing plate tapers outwardly in a directionaxially away from the rotors.
 2. A rotary internal combustion enginecomprising two rotors mounted within a housing for rotation aboutrespective central axes which are substantially parallel to each other,each rotor having a series of radially projecting lobes which areequally spaced circumferentially and which intermesh with the lobes ofthe other rotor to form successive combustion chambers as the rotorsrotate, said housing being provided with a sealing plate on each axialside of the rotors, the sealing plates being in sealing engagement overan active area which axially seals each combustion chamber formed by therotating intermeshing rotors throughout a full combustion cycle, whereinfour intermeshing rotors are provided in two pairs, the central axes ofthe rotors being provided on the corner of a square, each pair of rotorsproviding said successive combustion chambers which are axially sealedby said sealing plates and wherein each sealing plate is generallydiamond shaped, the short axis of which is generally parallel toimaginary lines extending beyond the central axes of each pair ofrotors.
 3. A rotary internal combustion engine comprising two rotorsmounted within a housing for rotation about respective central axeswhich are substantially parallel to each other, each rotor having aseries of radially projecting lobes which are equally spacedcircumferentially and which intermesh with the lobes of the other rotorto form successive combustion chambers as the rotors rotate, saidhousing being provided with a sealing plate on each axial side of therotors, the sealing plates being in sealing engagement over an activearea which axially seals each combustion chamber formed by the rotatingintermeshing rotors throughout a full combustion cycle, and wherein atleast one of the sealing plates provides orifices for fuel delivery tothe combustion chamber.
 4. An engine as claimed in claim 3 wherein atleast one of the sealing plates provides ignition means.
 5. A rotaryinternal combustion engine comprising two rotors mounted within ahousing for rotation about respective central axes which aresubstantially parallel to each other, each rotor having a series ofradially projecting lobes which are equally spaced circumferentially andwhich intermesh with the lobes of the other rotor to form successivesealed combustion chambers, each lobe having a tip and a leading face inthe direction of rotation, each tip and each leading face being providedwith an axially extending strip seal arrangement each comprising anaxially extending through slot formed in the rotor and a pair of axialseal elements retained in the slot, the axial seal segments each havinga portion projecting beyond the rotor and being of the same axial lengthas the rotor, wherein each axial through slot has a first sectionopening to a second section inwardly thereof, the second section beingwider than the first section such that the axial slot retains the axialseal segments.
 6. An engine as claimed in claim 5 wherein each pair ofaxial seal segments are mirror images of each other and have abuttingplanar surfaces.